Multi-Gene Analyses of the Phylogenetic Relationships among the Mollusca,

analyses of the phylogenetic relationships among the Mollusca, Annelida, and Arthropoda. Zoological Studies 47(3): xxx-xxx. The current understanding of metazoan relationships is largely based on analyses of 18S ribosomal RNA (‘18S rRNA’). In this paper, DNA sequence data from 2 segments of 28S rRNA, cytochrome c oxidase subunit I, histone H3, and U2 small nuclear (sn)RNA were compiled and used to test phylogenetic relationships among the Mollusca, Annelida, and Arthropoda. The 18S rRNA data were included in the compilations for comparison. The analyses were especially directed at testing the implication of the Eutrochozoan hypothesis that the Annelida and Mollusca are more closely related than are the Annelida and Arthropoda and at determining whether, in contrast to analyses using only18S rRNA, the addition of data from other genes would reveal these phyla to be monophyletic. New data and available sequences were compile